|
In medicine, melena or melæna refers to the black "tarry" feces that are associated with upper gastrointestinal bleeding.〔, retrieved 19 July 2010.〕 The black color is caused by the hemoglobin in the blood being altered by digestive chemicals and intestinal bacteria. Iron supplements may cause a grayish-black stool that should be distinguished from the black, tarlike stool that occurs from bleeding ulcer. ==Causes== The most common cause of melena is peptic ulcer disease. Any other cause of bleeding from the upper gastrointestinal tract, or even the ascending colon, can also cause melena. Melena may also be a sign of drug overdose if a patient is taking anticoagulants, such as warfarin. It is also caused by tumors, especially malignant tumors affecting the esophagus, more commonly the stomach & less commonly the small intestine due to their bleeding surface. However,the most prominent and helpful sign in these cases of malignant tumors is haematemesis. It may also accompany hemorrhagic blood diseases (e.g. purpura & hemophilia). Other medical causes of melena include bleeding ulcers, gastritis, esophageal varices, Meckel's diverticulum and Mallory-Weiss syndrome. Causes of "false" melena include iron supplements, Pepto-Bismol, Maalox, and lead, blood swallowed as a result of a nose bleed (epistaxis), and blood ingested as part of the diet, as with consumption of black pudding (blood sausage), or with the traditional African Maasai diet, which includes much blood drained from cattle. Melena is often a medical emergency as it arises from a significant amount of bleeding. Urgent care is required to rule out serious causes and prevent potentially life-threatening emergencies. A less serious, self-limiting case of melena can occur in newborns two to three days after delivery, due to swallowed maternal blood. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「melena」の詳細全文を読む スポンサード リンク
|